Synthesis and Characterization of Partially Renewable Oleic Acid-Based Ionomers for Proton Exchange Membranes

Abstract

The future availability of synthetic polymers is compromised due to the continuous depletion of fossil reserves; thus, the quest for sustainable and eco-friendly specialty polymers is of the utmost importance to ensure our lifestyle. In this regard, this study reports on the use of oleic acid as a renewable source to develop new ionomers intended for proton exchange membranes. Firstly, the cross-metathesis of oleic acid was conducted to yield a renewable and unsaturated long-chain aliphatic dicarboxylic acid, which was further subjected to polycondensation reactions with two aromatic diamines, 4,4′-(hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline and 4,4′-diamino-2,2′-stilbenedisulfonic acid, as comonomers for the synthesis of a series of partially renewable aromatic-aliphatic polyamides with an increasing degree of sulfonation (DS). The polymer chemical structures were confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H, 13C, and 19F NMR) spectroscopy, which revealed that the DS was effectively tailored by adjusting the feed molar ratio of the diamines. Next, we performed a study involving the ion exchange capacity, the water uptake, and the proton conductivity in membranes prepared from these partially renewable long-chain polyamides, along with a thorough characterization of the thermomechanical and physical properties. The highest value of the proton conductivity determined by electrochemical impedance spectroscopy (EIS) was found to be 1.55 mS cm−1 at 30 °C after activation of the polymer membrane.

Synthesis and Characterization of Thiol-Functionalized Polynorbornene Dicarboximides for Heavy Metal Adsorption from Aqueous Solution

“…From Figure 5, it can be seen that all the thiol-functionalized polymers show the onset temperature for decomposition (T d ) in the range of 409-459 • C, indicating that the norbornene dicarboximide monomers reported here yield polymers of relatively high thermal stability. The polymer density, ρ, was measured in film form by the flotation method at ambient conditions in ethanol [25]. In Table 1, it is noticed that polymer 2a exhibits the higher density of all the polymers studied here, which could be associated with a higher polymer chain packing efficiency promoted by the thiol groups.…”

Synthesis, Characterization, and Proton Conductivity of Muconic Acid-Based Polyamides Bearing Sulfonated Moieties

“…Table 4 shows some of these materials, along with their ionic properties, and compares them with the values obtained for the muconic acid-based polymers developed in this research. The results obtained for the Various efforts have been made to develop sulfonated polymeric materials with a sustainable approach around the world [36][37][38][39][40]. Table 4 shows some of these materials, along with their ionic properties, and compares them with the values obtained for the muconic acid-based polymers developed in this research.…”

“…Due to the latter reason, it also shows the highest IEC and Wu values, which in turn is reflected in the highest proton conductivity of all the materials synthesized in this study. Various efforts have been made to develop sulfonated polymeric materials with a sustainable approach around the world [36][37][38][39][40]. Table 4 shows some of these materials, along with their ionic properties, and compares them with the values obtained for the muconic acid-based polymers developed in this research.…”